Existing developer rollers which this invention replaces are semiconductive rubber with a thin, outer insulation layer of polyurethane. Such rollers have a conductive center shaft to which an electrical potential is applied which is approximately one-half of the potential to which non-image areas of a photoconductive surface are charged, with the image areas being substantially at zero volts. Toner powder is separately charged, applied to the developer roller, and regulated in thickness and charge by an electrically charged doctor blade as the developer roller is turned. The developer roller then makes nip contact with the photoconductive surface, which typically is a roller or belt moving with the developer roller.
A developer roller of one material on the shaft having interchangeable function with the existing roller has significant potential savings in manufacture since it would not require a separate coating. This invention provides such a roller in which the material is metal-salt-containing urethane which may be molded on the core in one step.
U.S. Pat. No. 4,257,699 to Lentz teaches a wide range of metals including specific mention of copper chloride in a multilayer fuser roller, while the subject invention is a single layer developer roller. This patent also teaches inclusion of silicone oil, which is a beneficial, but not essential, ingredient in the subject invention. U.S. Pat. No. 4,710,015 to Takeda et al teaches a two layer developer roller with additives of copper, nickel and carbon black.